Detergents have long been recognized as reagents for solubilizing many biochemicals, particularly microbial proteins and protein complexes. This ability is useful for liberating or exposing antigens in the proteins which subsequently may be detected by immunoassay techniques. Unfortunately, however, detergent in an antigen solution inhibits immunoassay by preventing the binding of the antigen to a solid phase immobilized antibody. Heretofore, no practical, inexpensive method has been available for eliminating this adverse effect of detergent on immunoassay. Simply diluting the sample is unsatisfactory. For example, if the immunoassay sample is diluted after solubilization so that the concentration of detergent no longer affects the assay procedure, the concommitant reduction in antigen concentration results in an antigen level which is below the assay threshold sensitivity. Similarly, increasing the initial concentration of antigen in the immunoassay sample such that the concentration of antigen after dilution is above the sensitivity threshold is often not practical, as sample specimens are often of necessity small. There is thus a need in the art for a method of detergent solubilization of proteins which does not simultaneously inhibit immunoassay procedures.
A specific application where detergents can be used beneficially is in the solubilization of the principal outer membrane protein of Chlamydia trachomatis. This microorganism is one of the two species of the genus Chlamydiaceae, order Chlamydiales. The other species is Chlamydia psittaci. Chlamydia trachomatis in its some 15 various strains is the etiologic agent for a number of human ocular and genital diseases, including trachoma, inclusion conjunctivitis, lymphogranuloma venereum, "nonspecific" or nongonococcal urethritis and proctitis. C. trachomatis infection is pervasive throughout the general population. It has been estimated, for instance, that C. trachomatis is accountable for several million cases per year of nongonococcal urethritis.
Since C. trachomatis mediated disease is widespread, a reliable, simple and inexpensive test for the organism's presence is highly desirable and of great importance so that proper treatment can be undertaken. The only serological test in current use is the microimmunofluorescence test. This test, however, requires that the strains of C. trachomatis be used as serological test antigen. In addition, the facilities for conducting this test are available in only a limited number of laboratories throughout the world. The test is very laborious, time consuming and difficult to perform.